The 17th-ranked Bruins dropped a 151-92 decision to the second-ranked team in the country.
The Bruins are 7-1 in duals this season, but face their toughest tests of the year this weekend.
Annika Lenz followed up a pair of fourth-place springboard finishes with a second on Monday.
Polyakova and Lenz have finished Top 5 on both days of the Bruin Diving Invitational.
Annika Lenz was fourth in Saturday's 3-Meter, Maria Polyakova was fifth and Ciara Monahan seventh.